Circuit interrupter



Och 1962 w. M. LEEDS 3,060,294

CIRCUIT INTERRUPTER Filed Oct. 30, 1957 2 SheetsSheet 1 Fig.l.

Fig.3.

4 Air 4 3l ummmmn mm J? [A k/// I I J 34 WITNESSES INVENTOR WK 4W Winthrop M. Leeds BY i WM WKW ATTORNFY United States Patent 3,060,294 CIRCUIT INT ERRUPTER Winthrop M. Leeds, Forest Hills, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed Oct. 30, 1957, Ser. No. 693,306 8 Claims. (Cl. 200-148) This invention relates to circuit interrupters in general and, more particularly, to arc-extinguishing structures and operating mechanisms therefor.

In U.S. patent application filed January 22, 1957, Serial No. 635,400, now Patent No. 2,981,814, by Robert E. Friedrich, entitled, Circuit Interrupters, and assigned to the assignee of the instant application, there is disclosed and claimed a type of circuit interrupter utilizing a serially related pair of arc-extinguishing units disposed at the opposite ends of a single terminal bushing, each of the units being disposed within a surrounding weatherproof porcelain casing. The units were of the puffer type, in which a piston and orifice, movable with the movable contact, reciprocally operate within an operating cylinder to force compressed gas through the orifice to effect eX- tinction of the are established therein.

It is a general object of the present invention to improve upon the circuit interrupter described in the aforesaid application, and particularly to bring about more effective and rapid operation by the utilization of a hydraulic operating mechanism.

Another object of the invention is to provide an improved hydraulic operating mechanism for a pair of serially related arc-extinguishing units, in which the operation of the two movable contact structures is synchronized mechanically so that assurance may be had that both arc-extinguishing units are operating in a satisfactory manner by opening and closing substantially simultaneously.

Still a further object of the invention is to provide an improved hydraulic operating mechanism for a circuit interrupter utilizing arc-extinguishing units, each of which effects the compression of gas, in which an improved seal is provided to prevent the contamination of the hydraulic operating fluid with the arc-extinguishing gas.

Another object of the invention is to provide an improved circuit interrupter utilizing a pair of serially related arc-extinguishing units in which an improved indicator devce is employed to positively indicate the open and closed-circuit positions of the movable contact.

A further object of the invention is to provide an improved circuit interrupter in which the one or more arcextinguishing units are supported upon an upwardly extending insulating pedestal serving as a gas reservoir chamber, in which the interior of the insulating reservoir pedestal is hollow and filled with a compressed gas of relatively high dielectric strength.

Yet a further object of the invention is to provide an improved circuit interrupter of the type specified in the immediately preceding paragraph, in which the upstanding pedestal in addition serves as a conduit for the arcextinguishing gas to the one or more interrupting chambers.

Another object is to provide an improved hydraulic operating mechanism in which gas pressure is employed upon the liquid level in the sump, so that a positive pressure exists at all times in the control line leading from the pilot valve to the main operating valve. This prevents air leakage into the control line by such positive pressure.

A further object is to provide an upstanding pedestal gas reservoir for a circuit interrupter in which suitable check valves are employed in the feed lines leading from the pedestal reservoir so that contaminated, arced gas will not be forced under pressure back into the gas reservoir pedestal, and breakage of the pedestal reservoir will not affect the maintenance of gas pressure over the liquid level in the sump.

Further objects and advantages will readily become apparent upon reading the following specification, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a side elevational view of a circuit interrupter embodying the principles of the present invention, with the contact structure being indicated in the closed-circuit position;

FIG. 2 is a fragmentary, enlarged, partly diagrammatic, vertical sectional view through a portion of the upper end of the circuit interrupter of FIG. 1, with the contactv structure being likewise shown in the closed-circuit position; and,

FIG. 3 is a fragmentary, top plan view of a portion of the circuit interrupter of FIG. 2, with a portion of the intermediate housing broken away to illustrate the indicator mechanism, again the contact structure being indicated in the closed-circuit position.

Referring to the drawings, and more particularly to FIG. 1 thereof, the reference numeral 1 generally designates a circuit interrupter of the type including a pair of laterally extending arc-extinguishing units 2 (FIG. 2), enclosed within horizontally extending weatherproof casings 3, in this particular instance being made of porcelain.

The inner ends of the porcelain casings 3 are secured to ring-shaped mounting flanges 4 by cement 5, and, as shown in FIG. 2, the porcelain casings 3 are supported in a horizontal manner, extending laterally outwardly from an intermediate mechanism housing 7. The interior 8 of the intermediate mechanism housing 7 is preferably filled with air at atmospheric pressure.

The intermediate mechanism housing 7 is supported at the upper end of an upstanding insulating gas reservoir pedestal 9, more clearly shown in FIG. 1. The pedestal 9 is formed from a suitable Weatherproof material, in this particular instance porcelain. The pedestal 9, in

turn, is supported on top of .a lower mechanism compart-.

ment 10, which may have a door 11 opened by a manually operable handle 12. The mechanism compartment 10 may rest upon any suitable base 13.

As more clearly shown in FIG. 2, each of the two serially related arc-extinguishing units 2 includes an insulating operating cylinder 14, supported at the end of a hydraulic operating cylinder 15. Reciprocally movable within the operating cylinder 14 is a piston 16 having a laterally jutting orifice portion 17. The piston 16 is carried by a movable contact 18, the latter being disposed at the end of a contact rod 19. Located at the inner end of the contact rod 19 is a differential piston, generally designated by the reference numeral 20.

Cooperable with the movable contact 18 is. a relatively stationary contact 21, the latter being supported by a conducting closure cap 22. The closure cap 22 may have a terminal stud 23 afiixed thereto, to which may be connected an external line conductor, not shown.

As shown in FIG. 2, the closure cap 22 is secured, by any suitable clamping means, to a ring-shaped mounting flange 24, the latter being affixed, as by cement 25, to the outer end of the porcelain casing 3. Preferably the inner surface of the porcelain casing 3 has intersecting conical, tapered surfaces 26, intersecting at the point 27, for a purpose to be explained hereinafter.

Each of the two differential pistons 20 has a rack 28 secured thereto, as shown in FIG. 2, which racks 28 mesh with a pinion gear 29 fixed on a shaft 30, the latter extending outwardly from'the operating cylinder 15 in a manner more clearly illustrated in FIG. 3 of the drawings.

As illustrated in FIG. 3, the indicator shaft 30 has a Patented Oct. 23, 1962 pinion gear 31 keyed thereto adjacent its outer end, which pinion gear 31 meshes with a larger gear 32, the latter effecting the rotation of a second indicator shaft 33. Disposed externally of the intermediate mechanism housing 7, at the outer end of the indicator shaft 33, is an indicator pointer 34, the latter indicating the open and closed positions of the interrupter 1, as more clearly shown in FIG. 1 of the drawings.

The outer sides of each differential piston 20 is constantly maintained under high pressure, as caused by the presence of a high-pressure operating fluid, such as oil 35, disposed within a pair of opening conduits 36, the latter being connected together and with an enlarged supply conduit 37. The upper end of the hydraulic conduit 37 is connected to a high pressure accumulator, generally designated by the reference numeral 38.

The high-pressure accumulator 38 includes a reservoir tank 39, within which is situated a movable piston or diaphragm 40 biased downwardly under pressure by a suitable gas, such as nitrogen N disposed under pressure in the region 41 at the upper end of the reservoir tank 39. The nitrogen is preferably under high pressure, say 2,000 pounds per square inch gauge.

'It will be obvious, therefore, that the accumulator 38 maintains the hydraulic fluid, such as oil 35, under pres sure of 2,000 p.s.i. within the hydraulic conduits 36, thereby tending to force the differential piston 20 and hence the movable contact rods 19 toward each other in the opening direction.

To maintain the movable rods 19 in the closed-circuit position a hydraulic conduit 42 is connected to the hydraulic operating cylinder in back of the differential pistons 20, and since the contact rods 19 move out of the chamber 15, the effective closing area of the pistons. is greater than the effective opening area. Equal pressure conditions on both sides of the differential pistons 20 will, therefore, cause the movable contact structures 18 to remain in the closed-circuit position, as shown in FIG. 2.

The lower end of the hydraulic conduit 42 is connected to a main hydraulic valve, generally designated by the reference numeral 44. The main hydraulic valve 44 includes a casing 45, within which reciprocally moves a plunger piston 46, carrying a sleeve valve 47 through a spider 48. The sleeve valve 47 is biased downwardly by a compression biasing spring 49. In addition, the sleeve valve 47 has a plurality of, in this particular instance, four openings 50, which connect at all times an annular space 51, within casing 45, with the region 52 within sleeve valve 47.

The supply conduit 37, as shown in FIG. 2, connects with the space 53 within the upper end of the valve casing 45. Connected to the lower end of the valve casing 45 is a drain conduit 54, composed of insulating material and extending downwardly interiorly within the insulating gas reservoir pedestal 9. The lower end of the insulating drain conduit 54 communicates with a sump 55, located at ground potential within the mechanism compartment 10 (FIG. 1).

Disposed above the oil level 56 within the sump 55 is a suitable arc-extinguishing gas, such as sulfur hexafluoride SP maintained at a suitable lower pressure, such as 60 p.s.i. The SP at 60 p.s.i. within the region 57 of the sump 55 also communicates by way of conduit 58 and a check valve 58a to the region 59 interiorly of the insulating gas reservoir pedestal 9.

The sump 55 is also connected by a conduit 60 through a filter 61 to a compressor pump 62. The oil 35 may thus be pumped to a high pressure and fed through a conduit 63 upwardly interiorly through pedestal 9 back up into the supply conduit 37, and hence into the highpressure accumulator 38. A pilot valve 64 is provided in a conduit 65 interconnecting high-pressure conduit 63 and the low pressure drain 54. This pilot valve 64 controls the admission of high-pressure hydraulic fluid 35 from the conduit 65 upwardly through a control conduit or operating line 66. The upper end of the control conduit 66 terminates within a space 67 below the plunger piston 46. A drain conduit 68 interconnects the space 69 above the plunger piston 46 with the drain conduit 54.

The regions 70 within each porcelain casing 3 are connected by a conduit 71 through an upstanding feed conduit 72 and through a check valve 73 to the region 59 within hollow gas reservoir pedestal 9.

In the closed-circuit position of the interrupter the electrical circuit therethrough includes left-hand terminal stud 23, closure cap '22, stationary contact 21, movable contact 18, movable contact operating rod 19, conducting hydraulic operating cylinder 15 to the other conducting movable contact rod 19 and, in a similar manner, to the other line terminal stud 23, as shown in FIG. 1.

When it is desired to effect the opening of the circuit interrupter 1, the pilot valve 64 is operated, either manually or electromagnetically, to thereby permit highpressure hydraulic fluid, such as oil 35, to pass from the high pressure conduit 63, through control conduit 66 to space 67 below plunger piston 46. Since the space 69, above plunger piston 46, is connected by the drain conduit 68 to a relatively low pressure, the plunger piston 46 rapidly moves upwardly against the opposition afforded by biasing spring 49. This will cause the sleeve valve 47 to move upwardly, closing off the inlet region 53 of the main hydraulic Valve 44, and opening the outlet space 74 of main hydraulic valve 44, through conduit 42, with the space 75 on the back sides of the differential pistons 20. Since the space 76 on the front sides of the differential pistons 29 is constantly maintained at high pressure, the pistons 20' will be rapidly moved toward each other by the high-pressure hydraulic fluid 35 to thereby effect the separation of the movable contacts 18 away from the stationary contacts 21.

An arc, not shown, will be established between each pair of contacts 18, 21 within each orifice 17, and will be extinguished by the flow of fluid, such as SP com pressed within the space '77 back of each piston 16. This compressed SP will be forced out of the space 77, within the operating cylinder 14, through the insulating orifice 17, to effect extinction of the are drawn between the contacts 18, 21.

Since the motion of the two movable contact operating rods 19 is synchronized by the meshing of the two movable racks 28 with pinion gear 29, the two contact gaps will close simultaneously, dividing the voltage stresses substantially equally. Also on opening there will be established substantially equal arc-extinguishing conditions within each arc-extinguishing unit 2, so that each arc-extinguishing unit will contribute its full share to the interrupting effort.

To prevent the contamination of the SP with the hydraulic fluid, such as oil 35, there is provided at each outer end of the hydraulic operating cylinder 15 a sealing region 78, which is connected, by a drain pipe 79, to the main drain conduit 54. Thus, any high-pressure oil 35, which may leak along the contact rod 19 through the opening 80 within the hydraulic operating cylinder 15, will merely drain downwardly through the drain pipe 79 through drain conduit 54 to the sump 55. It will be noted that the pressure within the sealing region 78 is the same as the pressure within the region 70 within porcelain casing 3 so that, as a result, there will be no tendency for the SP to leak along the contact rod 19 through opening 81 within insulating operating cylinder 14.

The rotation of pinion gear 29, by the racks 28, will effect corresponding rotative movement of the indicator shaft 30, and hence, through the gears 31, 32 (FIG. 3) effect an external indicating movement of the indicator pointer 34, as more clearly illustrated in FIG. 3 of the drawings.

All the time that the units 2 are in the open circuit position, the pilot valve 64 remains in the position pers,0eo,294.

mitting high pressure oil to communicate with the space 67 beneath the plunger piston 46, thereby maintaining the slide valve 48 in its upper position, blocking off entrance region 53. This upward position of sleeve valve 48 is in opposition to the force of gravity and to the force afiorded by the biasing spring 49.

When it is desired to effect the closing of the circuit through the interrupter 1, the pilot valve 64 is manually or electromagnetically operated to its other position, so as to connect the space 67 below plunger piston 46 to the main drain conduit 54. The spring 49, and the force of gravity, will move the plunger piston 46 downwardly, it being apparent that now the pressure within the spaces 67, 69 are equal, as brought about the drain pipe 68. The downward movement of the slide valve 47 will close off the drain region 74 of main hydraulic valve 44 and will open up the inlet high-pressure region 53. Thus, highpressure oil 35 will pass through the high-pressure inlet region 53 across the upper end of sleeve Valve 47, through openings 50 and annular space 51, and through conduit 42 to the region 75 in back of the differential pistons 20. Since the rear faces of the difierential pistons 20 have a greater effective cross-sectional area than the front faces, as caused by the cross-sectional area of the contact rods 19, the movable contacts 13 will be moved outwardly from operating cylinder 15 and into contacting engagement with the stationary contacts 21. This will complete the electrical circuit through the interrupter 1.

It is to be understood that instead of employing oil 35, any suitable hydraulic fluid may be employed. In addition, instead of using SP any suitable arc-extinguishing gas may be utilized.

From the foregoing description it will be apparent that there is provided a high-speed hydraulically actuated circuit interrupter, in which the contact motion is synchronized. An equalizing seal is provided to prevent the contamination of the liquid with the arc-extinguishing fluid. Entrance of hydraulic oil into the heated arcing chamber might cause a chemical reaction between the oil vapors and the heated and arced SF gas. Division of voltage between the units 2 could be achieved by suitable capacitor tubes extending within the porcelain casings 3 for such voltage dividing purpose. Also, when using SP should the ambient temperature reach a sufiiciently low value to cause the condensation of SP the tapered interior surfaces of the porcelain casings 3 will provide ready drainage for the liquid SP The use of SP at 60 p.s.i. within hollow gas reservoir insulating pedestal 9 will improve the voltage-withstanding ability of the porcelain pedestal 9, and, in addition, will permit the pedestal 9 to serve as a conduit from the pipe 58 to the lower end of the feed conduit 72. Moreover, should pressure be lost within pedestal 9, as a result of cracking thereof or leakage, the check valve 73 will prevent the pressure dropping within the casings 3, thereby maintaining adequate dielectric strength between the contacts 18, 21 should they be separated at this time.

Also the check valve 73 will prevent the high arcing pressure within the regions 70 of the extinguishing units 2 from backing into the feed line 72 and forcing contaminated, arced gas back into the gas reservoir 9.

The check valve 58a will prevent a loss of pressure in the region 57 above the liquid level in the sump 55, should the porcelain casing 9 crack and lose its gas pressure.

An important feature of the invention is the maintenance of this gas pressure in the region 57 of sump 55, for this will maintain a positive pressure within control line 66, even though the latter is connected to the sump by pilot valve 64. Otherwise a negative pressure could exist in control line 66 by the height of the liquid therein, and air leakage through the seals for the line 66 might result.

Certain features of the circuit interrupter are set forth and claimed in United States patent application, Serial No. 693,309, filed October 30, 19-57, by Albert P. Strom, and assigned to the assignee of the instant application.

Certain features of the master control valve 44 are described and claimed in United States patent application, Serial No. 709,233, now Patent No. 3,008,017, filed January 16, 1958, by Albert P. Strom and William H. Fischer and assigned to the same assignee as the present application.

Although there has been shown and described a specific structure, it is to be clearly understood that the same was merely for the purpose of illustration, and that changes and modifications may readily be made therein by those skilled in the art, without departing from the spirit and scope of the invention.

I claim as my invention:

1. A circuit interrupter including a sealed casing. containing an arc extinguishing gas, separable contacts disposed within said sealed casing separable to establish an are, a movable contact rod for effecting the movement of one of said separable contacts, a hydraulic mechanism for actuating said movable contact rod including a hydraulic operating cylinder, a hydraulic piston secured adjacent one end of said movable contact rod and movable within said hydraulic operating cylinder, means defining a bore out of said hydraulic operating cylinder along which said movable contact rod moves, a sealing chamber disposed along said bore of the hydraulic operating cylinder and containing said arc-extinguishing gas, a drain for said sealing chamber, and the gas pressure of the arc-extinguishing gas within said sealing chamber being substantially the same as the gas pressure adjacent the separable contact within said sea'led casing in the closed circuit position of the circuit interrupter.

2. A circuit interrupter including a sealed casing containing an arc extinguishing gas, separable contacts disposed within said sealed casing separable to establish an arc, a movable contact rod for effecting the movement of one of said separable contacts, a hydraulic mechanism for actuating said movable contact rod including a hy draulic operating cylinder, a hydraulic piston secured adjacent one end of said movable contact rod and movable within said hydraulic operating cylinder, means defining a bore out of said hydraulic operating cylinder along which said movable contact rod moves, a sealing chamber disposed along said bore of the hydraulic operating cylinder and containing said arc-extinguishing gas, a drain for said sealing chamber, and the gas pressure of the arcextinguishing gas within said sealingchamber being substantially less than the hydraulic driving pressure.

3. A circuit interrupter including separable contacts, a movable contact rod for effecting the movement of one of the separable contacts, a hydraulic mechanism for actuating said movable contact rod including a hydraulic operating cylinder, a hydraulic piston movable within said hydraulic operating cylinder and secured adjacent one end of said movable contact rod, said hydraulic operating cylinder having a bore through one wall thereof through which the movable contact rod moves, a sealing chamber disposed along said bore of the hydraulic operating cylinder, a drain for said sealing chamber, and said sealing chamber containing gas at a relatively low pressure compared to the hydraulic driving pressure.

4. A circuit interrupter of the gas blast type including an upstanding hollow insulating pedestal, one or more sealed interrupting units supported from the upper end of said hollow pedestal, arc-extinguishing means including piston putter means disposed in at least one sealed interrupting unit, hydraulic operating means at high potential for actuating said piston puffer means, a gas under pressure within said sealed interrupting units, and the same gas at substantially the same pressure completely filling said hollow pedestal.

5. A circuit interrupter including a hollow supporting pedestal completely filled with an arc-extinguishing gas under pressure, a sealed interrupter casing containing the same gas supported at the upper end of said supporting pedestal, arc-extinguishing means including piston puffer means disposed interiorly Within said sealed interrupter casing, hydraulic operating means for actuating said piston puffer means, and a gas feed conduit interconnecting the interior of said hollow supporting pedestal with the sealed interrupter casing so that the pressure of the gas within the sealed casing is substantially at the pressure of the gas within said hollow supporting pedestal.

6. A circuit interrupter including a pair of diverging sealed interrupter casings, a pair of relatively stationary contacts disposed at the outer extremities of the sealed interrupter casings, a pair of cooperable movable contact rods carrying gas-blast puffer pistons, a hydraulic operating mechanism for actuating said movable pair of contact rod-s including a hydraulic operating cylinder at high potential, a pair of hydraulic pistons secured to adjacent inner ends of said movable contact rods and reciprocally movable within said hydraulic operating cylinder, means for constantly maintaining high hydraulic pressure upon the outer sides of the hydraulic pistons tending to effect opening operation thereof, means for reducing the hydraulic pressure between the hydraulic pistons relative to the pressure on the outer faces thereof, a movable rack associated with each hydraulic piston, :and a pinion gear disposed substantially centrally within said hydraulic operating cylinder and meshing with the two movable racks to synchronize the opening and closing motion of the pair of movable contact rods.

7. A circuit interrupter including a pair of diverging sealed interrupter casings, a pair of relatively stationary contacts disposed at the outer extremities of the sealed interrupter casings, a pair of cooperable movable contact rods carrying gas-blast puffer pistons, a hydraulic operating mechanism for actuating said movable pair of contact rods including a hydraulic operating cylinder at high potential, a pair of hydraulic pistons secured to adjacent inner ends of said movable contact rods and reciprocally movable within said hydraulic operating cylinder, means for constantly maintaining high by draulic pressure upon the outer sides of the hydraulic pistons tending to effect opening operation thereof, means for reducing the hydraulic pressure between the hydraulic pistons relative to the pressure on the outer faces thereof, a movable rack associated with each hydraulic piston, and a pinion gear disposed substantially centrally within said hydraulic operating cylinder and meshing with the two movable racks to synchronize the opening and closing motion of the pair of movable contact rods, and an indicator shaft connected to said pinion gear and extending through the Wall of the hydraulic operating cylinder to give an external indication of contact rod position.

8. A circuit interrupter including a pair of diverging sealed interrupter casings, a pair of relatively stationary contacts disposed at the outer extremities of the sealed interrupter casings, a pair of cooperable movable contacts movable toward each other and carrying gas-blast putter pistons, a pair of movable contact rods supporting said pair of movable contacts and having a pair of actuating pistons secured thereto at the inner ends thereof, a fluid motor at high potential having a single operating cylinder within which is disposed said pair of actuating pistons, rectilinear motion of said actuating pistons away from each other within said single operating cylinder eflecting closing motion of said pair of movable contact rods and movable contacts, a movable rack associated with each actuating piston, a pinion gear disposed substantially centrally Within said single operating cylinder and meshing with the two movable racks to synchronize their motion, said fluid motor having a source of highpressure fluid, and valve means for admitting highpressure fluid from said source to the region within said single operating cylinder between the actuating pistons to eflfect simultaneous outward closing motion of the pair of movable contact rods, and a rotatable indicator shaft connected to said pinion gear and extending through a wall of said operating cylinder to eflect an external indication of the position of the movable contacts.

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